1. Field of the Invention
The present invention relates to an X-ray computed tomographic apparatus having an asymmetrical X-ray detector.
2. Description of the Related Art
The asymmetrical X-ray detector includes an X-ray detector in which a detection region of X-ray that passes through an object is asymmetric with respect to an imaging center line in a channel direction. In detail, in the asymmetrical X-ray detector, the imaging center line is disposed between X-ray detecting channels, and the number of X-ray detecting channels that is positioned at one side of the imaging center line is larger than the number of X-ray detecting channels that is positioned at the other side of the imaging center line. Further, the asymmetrical X-ray detector includes a multichannel X-ray detector in which the center is shifted from a line connecting a focal point of the X-ray and a rotating center of a tube toward the channel direction.
In accordance with the asymmetrical property of the detector, an X-ray beam is formed to be an asymmetrical sectorial formed by a slit. The asymmetrical X-ray detector can have a wider field of view for imaging (hereinafter, referred to as imaging FOV) than a symmetrical X-ray detector having the same number of channels. This X-ray detector is applicable when determining a portion to be treated by raising a right arm to image.
When a reconstructing process is performed on a tomographic image, a portion whose data is lost is supplemented by a complementary data to secure a field of view of reconstructing (hereinafter, referred to as reconstructing FOV) having the same level as the imaging FOV.
When a flat transmission image such as an X-ray image is acquired by a scanogram method, the image is configured by an asymmetrical channel arrangement. Therefore, the right and left of the imaging region are not symmetric to each other. The situation where the image is partially lost is not unavoidable in the case that the object is relatively large. As a result, it is needed to set a scanogram angle the by considering the above fact.
However, since a portion in which some of the image is lost is changed in a top or bottom, left or right direction corresponding to the position of the X-ray tube, it is difficult to be able to perceive the loss of the partial image. Further, the operability is bad.